262 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1923 



South Africa and those in Arkansas are in solid rock or in soft 

 residual material overlying it. All such rocks in both South Africa 

 and Arkansas belong to the variety known as peridotite, which in 

 both regions fills narrow volcanic craters and necks. 



Peridotite contains comparatively small proportions of silica and 

 alumina but much magnesium and iron. It invariably contains the 

 mineral olivine, but usually includes a rather large proportion of 

 brown mica and small proportions of other minerals. It is the only 

 rock that is known to be the original source of paying quantities of 

 diamonds. 



The peculiar type of diamond-bearing peridotite that occurs in 

 South Africa has been called kimberlite, after the famous Kimberley 

 mine. The diamond-bearing rock of Arkansas, which is similar, is 

 also known as kimberlite. 



DISCOVERY 



On August 1, 1906, John W. Huddleston discovered diamonds on 

 his property on Prairie Creek, 2y 2 miles south-southeast of Mur- 

 f reesboro, Ark. One stone was submitted to the Mermod, Jaccard & 

 King Jewelry Co., of St. Louis, and a little later other stones were 

 examined by George F. Kunz, a gem expert, of New York. The 

 stones came from an area of weathered peridotite that had long been 

 recognized by geologists as similar to the diamond-bearing peridotite 

 of South Africa, so it was evident that an original source of diamonds 

 had been discovered in North America. 



The existence of peridotite in this part of Arkansas was known 

 as early as 1842. The first detailed report describing the geologic 

 relations and nature of the peridotite was published in 1889 by John 

 C. Branner, State geologist of Arkansas, and E. N. Brackett. 

 Branner, in an article published in 1909, states that at the time of his 

 field examination, in the late eighties, he recognized the peridotite 

 as the kind of rock in which diamonds occur in South Africa. He 

 spent many hours on his hands and knees looking for diamonds in 

 the gullies and over the bare surfaces of the decomposed rock, but 

 he did not dare mention at that time his suspicion that diamonds 

 might be found in that region, because any such suggestion would 

 have added fuel to the wild mining excitement that was then raging 

 farther north in Arkansas. 



The finding of the diamonds by Huddleston led to a search which 

 resulted in the discovery of three other exposures of peridotite. 



LOCATION 



Peridotite is exposed in four areas, all near Murfreesboro, Pike 

 County, Ark., three of which have produced diamonds. The ex- 

 posure first discovered lies 2y 2 miles south-southeast of Murfrees- 



